The present invention relates to a vibrating reed formed of, for example, a crystal, a vibrator having the vibrating reed, an oscillator having the vibrator, and an electronic device having the vibrator.
Conventionally, a tuning-fork-type crystal vibrating reed is constructed as shown in, for example, FIG. 11.
More specifically, a tuning-fork-type crystal vibrating reed 10 comprises a base 11, and two vibration arm sections 12 and 13 formed so as to protrude from the base 11. In these two vibration arm sections 12 and 13, as shown in FIG. 12, grooves 12a and 13a are formed on the obverse surfaces and the rear surfaces thereof.
FIG. 12 is an enlarged sectional view along the Axe2x80x94Axe2x80x2 line in FIG. 11. As shown in FIG. 12, the vibration arm sections 12 and 13 are formed in such a manner that their cross sections are formed in nearly an H shape with the grooves 12a and 13a. 
Furthermore, as shown in FIG. 12, such grooves 12a and 13a are formed with groove excitation electrodes 12b and 13b for causing these vibration arm sections 12 and 13 to vibrate, respectively.
Furthermore, as shown in FIG. 12, side excitation electrodes 12c and 13c are also formed on the sides of the vibration arm sections 12 and 13, respectively.
The groove excitation electrodes 12b and 13b and the side excitation electrodes 12c and 13c are arranged with a fixed spacing therebetween, as shown in FIG. 12, so that these are not short-circuited with each other.
That is, when a voltage is applied to the groove excitation electrodes 12b and 13b and the side excitation electrodes 12c and 13c, an electric field is generated inside the vibration arm sections 12 and 13 at the portions which are held between these electrodes, and vibration starts.
Therefore, when the groove excitation electrodes 12b and 13b and the side excitation electrodes 12c and 13c are short-circuited, it becomes difficult for an electric field to be generated inside the vibration arm sections 12 and 13, causing the tuning-fork-type crystal vibrating reed 10 to malfunction.
The larger the widths (in the horizontal direction in FIG. 12) of the grooves 12a and 13a of such a tuning-fork-type crystal vibrating reed 10 are, the better the characteristics such as CI value (crystal impedance) becomes. For this reason, the widths of the grooves 12a and 13a are formed as large as possible.
As a consequence, the spacing between the groove excitation electrodes 12b and 13b and the side excitation electrodes 12c and 13c is small. As a result, even if a small amount of dust falls between the groove excitation electrodes 12b and 13b, and the side excitation electrodes 12c and 13c, a short-circuit is likely to occur, and the vibration of the vibration arm sections 12 and 13 may malfunction.
Meanwhile, in order to prevent a short-circuit which causes such a vibration malfunction, if an insulation film is arranged in an electrode section, the CI value (crystal impedance or equivalent series resistance) increases, and a problem arises in that the performance of the entire vibrating reed is deteriorated.
An object of the present invention is to provide a vibrating reed capable of making it difficult for a vibration failure to occur while minimizing the CI value, a vibrator having the vibrating reed, an oscillator comprising the vibrator, and an electronic device comprising the vibrator.
According to the present invention, preferably, vibrating reeds from (1) to (7) below are provided.
(1) A vibrating reed comprising: a base; and a vibration arm section formed so as to protrude from this base, a grooved portion being formed in one of a first or obverse surface and a second or rear surface of the vibration arm section, and a groove electrode portion and a side electrode portion being formed in the grooved portion and the side portion of the vibration arm section, respectively, wherein a short-circuit prevention section is formed between the groove electrode portion and the side electrode portion.
(2) A vibrating reed, wherein the groove electrode portion and the side electrode portion are excitation electrodes.
(3) A vibrating reed, wherein the short-circuit prevention section is formed of an insulation film.
(4) A vibrating reed, wherein the insulation film is formed in an etching step.
(5) A vibrating reed, wherein a cut section is formed in the base.
(6) A vibrating reed, wherein the base is provided with a fixation area for fixing this vibrating reed, and the cut section is provided in the base between the fixation area and the vibration arm section.
(7) A vibrating reed, wherein the vibrating reed is a tuning-fork-type vibrating reed formed from a crystal which oscillates at approximately 30 kHz to at approximately 40 kHz.